February, ’24] 
HAMLIN: PRICKLY PEAR PROBLEM 
63 
complex, attacking every part of the plant in a variety of ways. Sixteen 
species create the primary injury and seven scavengers assist by extend¬ 
ing this damage. The plant feeders include- two moth-borers (. Melitara ), 
destroying the joints internally; three coreids ( Chelinidea ) and two coch¬ 
ineals (Dactylopius) , devitalizing the joints externally; one pyralid 
(.Mimorista ) destroying the new growth externally; one pyralid ( Noc- 
tuelia) destroying the green fruits internally; one cecidomyiid ( Asphon- 
dylia) , inhibiting the development of seeds; one cerambycid ( Moneilema ), 
injuring the roots internally; one coreid (Narnia), devitalizing the fruits 
externally; and four weevils (Gerstaeckeria) , injuring the joints internally. 
The secondary insects include seven dipterous scavengers: five syrphids 
(Volucella and Copestylmn) and two stratiomyids (Hermetia ). 
The American phase of the project consisted in collecting the selected 
species, breeding free from parasites, packing to withstand the long 
journey, and shipping them under the most favorable conditions. Space 
prohibits presenting these phases. 
The Insects in Australia 
All of the species reached Australia alive but only 14 were reared there. 
Nine species proved effective, and five of these have increased rapidly. 
Shipping across the equator to directly opposite seasons has con¬ 
stituted a great difficulty in establishing the insects. 
The cochineals propagate most rapidly. The pyralid attacking new 
growth reproduces monthly during the long summer. The moth-borer 
of Texas sustains a larval mortality of 80 percent, due largely to crowd¬ 
ing, and yet increases each generation at the ratio of about 16 to 1. 
This two-brooded species has three broods in Australia, and now numbers 
over one million individuals in Australian laboratories. 
Tests of the cactus insects on economic plants will be completed by 
May next, when the desired and desirable species will be liberated. 
The Outlook 
Several of the introduced insects promise much damage to Australian 
pear in the absence of their natural enemies. The detrimental influence 
to be exerted against the newcomers by Australian parasitic and pre¬ 
daceous forms is largely problematical. Several ants are known to 
destroy the lepidopterous larvae and hemipterous nymphs, while the 
cochineals will be greatly handicapped. However, we have already 
seen that certain species increase rapidly despite a heavy mortality. 
The failure successfully to establish the American scavengers promises 
